The invention relates to a work piece installing and clamping device in an ion beam polishing process and a method thereof. The work piece installing and clamping device comprises a four-groove rotary platform which is fixed on a clamping main platform, wherein four grooves are symmetrically distributed on the four-groove rotary platform in orthogonal mode, four slide fixing columns are respectively arranged on the four grooves of the four-groove rotary platform, the slide fixing columns can be fixed or loosened by screwing fixing bolts on the slide fixing columns, ceramic cap pieces are fixed on the upper surfaces of the slide fixing columns, a hanging hook is respectively positioned on the lateral faces of the slide fixing columns, and a lifting support structure is respectively installed and clamped on the slide fixing column on the lower side of the hanging hook. The work piece installing and clamping method is that the four-groove rotary platform is fixed on the clamping main platform, work pieces can be installed and clamped on the four-groove rotary platform structure through the slide fixing columns, and the distance between the work piece and the slide fixing columns can be measured by utilizing a dial gauge to rorate the four-groove rotary platform, the positions of the slide fixing columns can be moved to adjust the same distance to guarantee center uniformity of the centers of the work pieces and the installing and clamping main platform, and accordingly accurate installing and clamping of the positions of the work pieces are achieved.